S r = ,.T 2 , where 
26 BULLi.ii \ 1216, r. s. 1)i;pai;t:\h;xt of ALRtrULTURE. 
:». The balance used shall be sensitive to 0.05 gram when loaded 
with 1 kilogram and weighings shall he read «t least to the 
nearest .mam. When other than metric weights are used, the 
same order of accuracy must he obtained. In reweighing after 
immersion, the specimens shall he removed from the water, not 
allowed to drain more than one minute, the superficial water 
removed by towel or blotting paper, and the specimens at once 
put upon the balance. 
4. Specimens after weighing shall be placed in a suitable re- 
ceptacle, covered with distilled water or ruin water, raised to 
the boiling point and boiled for five hours, and then cooled in 
water to a final temperature of 10° to l.", 0. (50 8 to 59° F.). 
5. The tesl results shall he calculated as percentages of the Ini- 
tial dry weight carried to the nearest first decimal place The 
results shall be reported separately for each individual speci- 
men, together with the mean of the specimens comprising the 
s:nnple. 
TRANSVERSE TEST OF CONCRETE. 
Specimens for the transverse test shall be 12 inches wide, 8 
inches deep, and :'.<> inches long. They shall be tested by a center 
load over a 24-inch span. 
The methods of proportioning, mixing, molding, and curing of 
the test pieces shall he the same as for making specimens of 
concrete for the compression test. 
The modulus of rupture S* may be found from the following 
formula : 
36P 
bd'< 
P=eenter load in pounds. 
b=breadth of the slab in inches. . 
(7=deptb of the slab in inches. 
TESTS FOR QUALITY OF WATER TO BE USED IN 
CONCRETE. 
Acidity and 1. Acidity and alkalinity. — The acidity or alkalinity shall be 
alkalinity. determined with standard solutions of N/10 alkali or acid re- 
spectively, using not less than 200 cubic centimeters of the water 
under examination. PhenoJphthalein or methyl orange should be 
used as an indicator. Excessive acidity or alkalinity indicates the 
necessity for further tests. 
Total solids. 2. Total solids and Inorganic matter. — Five hundred cubic cen- 
timeters of the water shall he evaporated to dryness in a weighed 
dish. For this purpose a platinum dish of 100 to 200 cubic centi- 
meters capacity is found most convenient. The dish shall be 
nearly filled with the water and placed on a water bath, additional 
portions of the sample of water being added from time to time 
Until 500 cubic centimeters have been used. The contents of the 
dish shall be evaporated to dryness and the dish and contents 
cooled in a desiccator and weighed. The weight of the residue in 
grams divided by 5 is the percentage of total solids in the water. 
Organic 3. The total solids Obtained as described may consist of or- 
matter. guide matter, of inorganic matter, or of combinations of organic 
and inorganic mutter. The platinum dish shall be ignited at low 
red heat, and the darkening of the residue during the early 
stage of the ignition usually indicates the presence of organic mat- 
ter. The per cent loss on ignition at low red heat will usually 
be an indicator of the amount of organic matter, but it should 
be noted that some mineral salts tend to volatilize or partly de- 
compose on heating. 
4. The determination of the composition of the mineral matter 
in the water usually requires a complete chemical analysis of 
the total solids obtained by the evaporation of 500 cubic centi- 
meters or more, of the water, and is not generally undertaken 
